Plant Growth and Nutrient Uptake Effects from Humic Substances in Lignite.

Humic and fulvic acids may increase nutrient retention when applied to coarse-textured soils. Lignite is mined for electrical energy generation, but occurs in surplus during periods of low energy consumption. Humic and fulvic acids found in lignite may be used as an alternative to peat-based soil amendments. The objective of this study was to determine the effect of soil application of lignite on corn (Zea mays) growth and nutrient uptake. A greenhouse experiment was conducted as a randomized complete-block with a 5x3 factorial arrangement of treatments, replicated four times. A Stough sandy loam (coarse-loamy, siliceous, semiactive, thermic fragiaquic paleudults) was amended with 0, 35, 70, 140 and 280 Mg/ha (w/w). Lignite’s humic and fluvic concentrations were 7.8 and 14%, respectively. Fertilizer (10-34-0) was applied at rates of 0, 33.6 and 67.2 kg/ha to each of the five lignite/soil treatments. Plant height was measured in 7-day increments. At 28-d, aboveground biomass was collected, dried and weighed to determine biomass and nutrient content. Lignite/soil was analyzed for pH, organic matter (OM) and cation exchange capacity (CEC). Plant height, nitrogen (N) content, OM and CEC increased with the addition of lignite. Soil pH decreased incrementally from 7.8 (0 lignite) to 6.48 with increasing lignite rate. Lignite increased only soil magnesium and sulfur content. The data suggests lignite may be a potential substitute for peat-based soil amendments.